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/*
Challenge 102
TASK #1 � Rare Numbers
Submitted by: Mohammad S Anwar
You are given a positive integer $N.
Write a script to generate all Rare numbers of size $N if exists. Please
checkout the page for more information about it.
Examples
(a) 2 digits: 65
(b) 6 digits: 621770
(c) 9 digits: 281089082
*/
#include <iostream>
#include <cmath>
int ipow(int base, int exp) {
int result = 1;
for (;;) {
if (exp & 1)
result *= base;
exp >>= 1;
if (!exp)
break;
base *= base;
}
return result;
}
int invert_number(int r) {
int r1 = 0;
while (r != 0) {
r1 = r1 * 10 + (r % 10);
r = r / 10;
}
return r1;
}
bool is_perfect_square(int n) {
double s = sqrt((double)n);
if (floor(s) == s)
return true;
else
return false;
}
void print_rare(int n) {
int start = ipow(10, n - 1);
int end = ipow(10, n );
for (int r = start; r < end; r++) {
int r1 = invert_number(r);
if (is_perfect_square(r + r1) && r >= r1 && is_perfect_square(r - r1))
std::cout << r << std::endl;
}
}
int main(int argc, char* argv[]) {
if (argc != 2) {
std::cerr << "Usage: ch-1 N" << std::endl;
return EXIT_FAILURE;
}
else
print_rare(atoi(argv[1]));
}
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